As but one example of the importance of hemodynamic information, cerebral oxygen delivery is critical in maintaining cognitive function and in the successful development of the young brain. Cerebral blood flow is regulated to ensure sufficient oxygen delivery. However, this blood flow autoregulation may be disrupted due to illness, injury, or medical treatment; without longitudinal measurements of cerebral oxygen delivery practical for bedside measurements, clinicians must utilize proxy measurements (e.g., systemic oxygenation) to anticipate and prevent ischemic brain injury. When the assumptions underlying these proxy measurements fail, clinical interventions may be poorly chosen.
Diffuse Correlation Spectroscopy (DCS) and Diffuse Optical Spectroscopy (DOS; DOS may be considered equivalent to NIRS for purposes of this disclosure) devices have been used in the head and other organs to continuously measure blood flow, volume, and oxygenation at the bedside. Current clinical cerebral oxygenation monitoring techniques measure blood flow in large vessels (e.g., Doppler ultrasound), require transport to an imaging suite (e.g., MRI) or radioactive contrasts (e.g., PET), or are restricted to monitoring temporal trends (cerebral oximeters). Diffuse optics utilizes low power red light (non-ionizing), similar to that utilized in clinically ubiquitous pulse oximeters.
However, the clinical utility and inter-study comparisons of diffuse optics are somewhat limited by technical challenges and instrument variability, restricting widespread adoption of diffuse optical techniques. Thus, there is a long-felt need in the art for improved devices and methods for collecting and monitoring hemodynamic information in body tissues, including blood flow, volume, and oxygenation, as well as other data of interest.